The disclosure generally relates to a DC-DC converting circuit and, more particularly, to a multiphase DC-DC converting circuit and control circuit thereof.
A multiphase DC-DC converting circuit comprises a plurality of current channels for providing power to a load. The multiphase DC-DC converting circuit may not only provide a sufficient current for a rapidly varying load, but also possess the advantage of low ripples in the provided current. Therefore, the multiphase DC-DC converting circuits are widely adopted in a variety of applications.
In the multiphase DC-DC converting circuit, however, the control circuit of the multiphase DC-DC converting circuit should know the current of each current channels and the total current provided to the load so as to provide power to the load more equally with the current channels, to perform the over-current protection function, to ensure the normal operation of the multiphase DC-DC converting circuit, etc.
In U.S. Pat. Nos. 6,683,441, 7,064,528 and 7,928,704, several circuit architectures are proposed to detect the total current which the multiphase DC-DC converting circuit provides to the load. These circuit architectures comprises resistors, capacitors, amplifiers, and other circuit elements for generating a signal proportional to the total current which the multiphase DC-DC converting circuit provides to the load. There are, however, many restrictions on choosing the impedances of these circuit elements, and the design flexibility is limited. Besides, in some circuit architectures, the current detecting signals of the current channels are coupled with the non-inverting input of the amplifier. Because the impedance of the non-inverting input of the amplifier is very high, the currents may not flow into the non-inverting input of the amplifier. Moreover, there is no other current path at the non-inverting input of the amplifier. In these situations, the circuit design is more complicated and the hardware complexity is increased.
In the above circuit architectures, when the control circuit of the multiphase DC-DC converting circuit detects the total current provided to the load, the current detecting signals of the current channels flow through circuit elements. The temperatures of the circuit elements increase and accordingly the impedances of the circuit elements vary so that the detected signal may not be accurate. Thus, complicated temperature compensation mechanisms should be adopted to ensure the accuracy of the detected signal.